Is there a way to set specific dimensions in inches or an other measurment?
I expect the easiest way is to use the measuere it addon. This is included with blender so you just have to enable it.

In edit mode, select two vertices on opposite sides of the hole. Add a measure segment. Scale the mesh until the measurement shows the size you want, holding &#8679; Shift while scaling will allow for more precise adjustments. You will want to make sure the objects scale is 1.0 to get correct measurements. After you have resized the object, you can delete the measurement.